All cultivated forms of lettuce belong to the highly polymorphic species, Lactuca sativa, which is grown for its edible head and leaves. As a crop, lettuce is grown commercially wherever environmental conditions permit the production of an economically viable yield.
Lactuca sativa is in the Cichoreae tribe of the Asteraceae (Compositae) family. Lettuce is related to chicory, sunflower, aster, scorzonera, dandelion, artichoke and chrysanthemum. Lactuca sativa L. is one of about 300 species in the genus Lactuca. 
Lettuce cultivars are susceptible to a number of pests and diseases such as downy mildew (Bremia lactucae). This disease result in millions of dollars of lost lettuce crop throughout the world every year. Downy mildew (Bremia lactucae) is highly destructive of lettuce grown at relatively low temperature and high humidity. Downy mildew is caused by a fungus. Downy mildew causes pale, angular, yellow areas bounded by veins on the upper leaf surfaces. Sporulation occurs on the opposite surface of the leaves. The lesions eventually turn brown, and they may enlarge and coalesce. These symptoms typically occur first on the lower leaves of the lettuce, but under ideal conditions may move into the upper leaves of the head. When the fungus progresses to this degree, the head cannot be harvested. Less severe damage requires the removal of more leaves than usual, especially when the lettuce reaches its final destination.
Of the various species of aphids that feed on lettuce, the currant-lettuce aphid (Nasonovia ribisnigri) is the most destructive species because it feeds both on the leaves of the lettuce as well as deep in the heart of the lettuce, making it difficult to control with conventional insecticides. The lettuce aphid feeds by sucking sap from the lettuce leaves. Although direct damage to the lettuce may be limited, its infestation has serious consequences because the presence of aphids makes lettuce unacceptable to consumers.
Although several known lettuce cultivars exhibit resistance against disease, irrespective of lettuce type, all the lettuce cultivars affected produce a limited number of leaves that generally are of unequal size and diminished quality with respect to color and shape. This is a distinct disadvantage for processing purposes because leaves either need to be sorted based on size or they need to be cut to a smaller, more uniform size. The first option requires additional labor, with not all sizes usable. The second option has the disadvantage that it creates many cut surfaces, which then are subject to wound-induced browning, resulting in a greatly reduced shelf-life.
Although several known lettuce cultivars produce a large number of small, more uniform leaves (U.S. Pat. No. 6,320,104; US patent publication 20070022496; US patent publication 20100229255), there is a need for a combination of resistance to downy mildew B1:1-28 and Ca-V to Ca-VIII-resistance and currant-lettuce aphid Nr:0.
There exists a need, therefore, for a lettuce variety which exhibits a combination traits including resistance against downy mildew strains B1:1-28 and Ca-V to Ca-VIII (Bremia lactucae) and the Nr:0-biotype of Nasonovia ribisnigri and an extraordinary high number of leaves of substantially equal size.
Citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention.